Dombeya x cayeuxii

Dombeya x cayeuxii, nicknamed the Tropical Hydrangea, is an ornamental bush with irresistible exotic charm. Valued for its long winter flowering, it is adorned with bright pink flowers with a delicate fragrance, gathered in clusters and hanging from the stems. This vigorous bush, which can also form a small tree, also bears large decorative palmate leaves. Apart from its low resistance to frost and wind, Dombeya x cayeuxii is not difficult to cultivate in full sun or partial shade, in any well-drained soil. In a well-sheltered coastal garden, it can be planted as a standalone feature, nestled against a protective wall. Elsewhere, grow it in a large pot on the terrace, to be moved indoors in winter.

Dombeya x cayeuxii is a horticultural hybrid belonging to the Malvaceae family. It results from the cross-breeding between Dombeya wallichii and D. burgessiae, two species native to Madagascar and East Africa respectively. This hybrid was created in 1895 by H.A.F. Cayeux in Lisbon, Portugal. Compared to its parents, Dombeya x cayeuxii stands out for its more abundant flowering and better adaptation to temperate climates.

This vigorous shrub has a rounded, bushy habit, reaching 4 to 6 m in height and spread at maturity, when planted in the ground and left unpruned. It can also be trained into a small tree with a single trunk through appropriate pruning. When grown in a pot, its growth will be much more modest. Its growth is rapid, reaching its mature size in just a few years. The leaves are evergreen in winter if there is no frost. They are large, up to 20 cm long. They are generally trilobed and dark green with a slightly fuzzy texture. The sturdy, branched stems are covered in smooth, light brown bark.

The spectacular flowering occurs from late autumn to early spring. The inflorescences of Dombeya x cayeuxii are particularly notable for their structure and appearance. They take the form of pendulous hemispherical panicles, measuring between 12 and 15 cm in diameter. Each panicle is composed of a multitude of small individual flowers, each about 2 to 3 cm in diameter. The fairly bright pink flowers have 5 rounded petals and cluster into dense spheres, resembling pink snowballs. The flowers emit a sweet fragrance. The fruits, rarely seen in this hybrid, are dry, lightweight capsules. The root system of the Dombeya is fibrous and shallow, which facilitates transplantation but requires protection against wind. Its leaves are also very sensitive to wind and salt spray.

Dombeya x cayeuxii is a tropical bush that thrives in full sun but also tolerates partial shade. It prefers rich, well-drained, fertile soils that are not too dry. Adapted to USDA zones 9b to 11, its crown can withstand minimum temperatures around -3.8°C. The above-ground vegetation is destroyed as soon as frost occurs.

This "tropical hydrangea" can be used as a standalone specimen to become the focal point of a small, very sheltered coastal garden, as it deserves. Paired with other tropical plants, it creates wonderfully exotic scenes. Its combination with Calliandra surinamensis (Powderpuff Tree) with its pink and white tufts is perfect. Hibiscus rosa-sinensis (Chinese Hibiscus) adds an extra tropical touch with its large, colourful flowers. Callistemon viminalis 'Bright Pink', which produces pink bottlebrush flowers, will extend the flowering period between May and September. In regions with colder winters, it makes a very beautiful plant for an orangery, conservatory, or lightly heated greenhouse.